1. Field of the Invention
The present invention relates to apparatus for controlling the automatic opening and closing of a work clamping mechanism in conjunction with a tool post in a machine tool which processes potentially elongated workpieces, and may be used in profilers, horizontal boring machines, etc.
2. Description of the Related Art
Many workpieces machined in a profiler to provide parts of an airplane, etc., are made of a soft material such as an aluminum alloy. They are often made of a long rectangular material by grinding. Generally, many successively disposed clamping devices are used to clamp a workpiece.
In order to attach the workpiece using these clamping devices, the operator sets a plurality of clamping devices on a table to clamp the work.
When the workpiece thus clamped is machined, a tool is fed to machine the workpiece except at the clamped portions of the work. Then, the clamping positions are changed and those portions of the workpiece which are not subjected to machining are then machined.
Since the process in which a workpiece is temporarily clamped and machined and then the clamping positions are changed and the workpiece is again machined provides a low machining efficiency, the following process is employed in an effort to improve the machining efficiency. A plurality of identical workpieces which are clamped at different positions are prepared. Each time machining one of the workpieces is completed, another work set on a new jig is machined while the next preparation is being made.
When the first machining of all the workpieces is completed, the clamping positions are changed and the next scheduled workpiece is then machined. Thus, the availability of the machine tool itself and hence the machining efficiency are improved.
However, attaching a workpiece using conventional clamping devices consumes much time and labor into preparation because individual clamps must clamp the workpiece. In addition, the operator is required to attach a workpiece by tightening many clamps manually, so that the clamping forces can vary from one to another. If the workpiece is made of a thin soft aluminum alloy, the accuracy of finish may be adversely affected by the material of the work.
Machining is made on the workpiece except at the clamped portions of the work, so that the machining speed and hence the machining efficiency are undesirably low.
After machining all but the clamped portions, the clamping positions must be changed and the workpiece remachined. Therefore, the arrangements are troublesome. It is difficult to have a highly accurate finish for the machined portions of the workpiece.
The process is which a plurality of workpieces clamped similarly, are prepared and, when machining all the workpieces is completed, the clamping positions are changed and the next workpieces are machined requires a lot of preparation and the use of many clamps. Therefore, managing the clamps is troublesome and a reduction in the machining accuracy due to changing the clamping positions is not solved.
It is an object of the present invention to provide an apparatus for controlling the opening and closing of a workpiece clamping mechanism in a numerically controlled tool machine which reduces the amount of preparation required for a workpiece and hence improves the machining accuracy.
Other objects, features and characteristics of the present invention, as well as the methods of operation and functions of the related elements of the structure, and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following detailed description and the appended claims with reference to the accompanying drawings all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures.